1. Field of the Invention
This invention relates to an automatic device for scanning an object and producing machine instructions in response to certain features of the object and the commands of a machine operator.
2. Description of the Prior Art
There are devices known to those of ordinary skill in the art for scanning printed circuit boards or masks with the purpose of trying to better define features therein. For example, the Airmar et al reference, U.S. Pat. No. 4,059,787, discloses a method and apparatus to give a particular zone type printed circuit board a distinctive appearance with respect to surrounding areas on the surface of the printed board. The surface of the printed board is automatically scanned in a system of two rectilinear perpendicular coordinates by a device comprising at least one detector which is responsive to the distinctive appearance. The coordinates of the surface point for which the detector delivers a signal representing the presence of the distinctive appearance during the scanning are recorded in a coded form which can be later utilized. See column 1, lines 6-42 and column 6, lines 37-39. A linear photo-electric network consisting of photosensitive elements is aligned parallel to the Y axis and is used to scan a width of the circuit board and an X-Y table is used to effectuate relative displacement between the photo-electric network and the circuit board. See column 3, lines 24-27 and column 5, lines 20-24 and lines 47-50. A center-finding unit is employed to determine the coordinates of the center points of the holes to be drilled. See column 6, lines 19-24. Hole diameters are then determined by a diameter-selecting unit. See column 6, lines 22-25. The apparatus further includes a unit which serves to visualize the holes to be drilled. See column 6, lines 44-50.
Similarly, Baxter et al, U.S. Pat. No. 4,056,716 discloses an apparatus for scanning a manufactured circuit board and comparing it with a master pattern to produce signals representing the quality of the manufactured circuit board. See column 1, lines 10-12 and column 2, lines 11-14. The Baxter et al reference further discloses a transport which is used to carry the object to be inspected past a scanner. See column 2, lines 6-14.
The use of machinery to prepare tapes to operate numerically controlled machines is well-known to those of ordinary skill in the art. See, for example, Evans et al, U.S. Pat. No. 4,010,356 which discloses a tape preparation system for preparing tapes of the sort used to control numerically controlled machine tools and which includes a computer inter-connected to a visual display for the purpose of assisting in the preparation of the information stored on the tape.
It is further known to those of ordinary skill in the art to use a camera to scan a surface in order to locate point data. See for example, Pascoe et al, U.S. Pat. No. 3,602,638 which discloses such a system in conjunction with a specially programmed computer in order to prepare a control tape for a numerically controlled machine.
Digital Systems, Inc., a subsidiary of Resdel Industries, Arcadia, Calif., 91006 markets a printed circuit board tape programmer and inspection system under the mark Star--Trak. The system includes an "optical centering eye" which is in part the subject matter of U.S. Pat. No. 3,716,716. The system apparently works in the following manner. Positive circuit art work is placed on an X-Y table and duplicate art work is placed on an operator table. The operator moves a servo assisted locator stylus to a pad hole thereby causing the X-Y table to track the stylus movement. When the stylus reaches the pad area the "optical centering eye" takes over and centers the hole. An air button, or foot switch, is then pressed in order to punch the tape.
Many of the devices on the market that are used to produce tapes for numerically operated machinery require a great deal of dexterity and concentration on the part of the machine operator. An example of such a device is sold under the name Checkmate by Advance Controls, Santa Ana, Calif.
In general the prior art suffers from several drawbacks. First of all, they frequently rely to a great extent upon operator dexterity and alertness. Secondly, even the advanced types can be rather slow in their scanning abilities. Thirdly, their powers of recognition are often limited. And, fourthly, their operation is often limited to a single function such as the recognition of holes only or for the comparison of a master pattern with the object that has already been machined.